terça-feira, 6 de maio de 2014

East Antarctic Melting Could Raise Sea Levels By 10 To 13 Feet

A region of East Antarctica is more vulnerable than previously
thought to a massive thaw that could result in world sea levels rising
for thousands of years, a study found Sunday.
The study,
published in the journal Nature Climate Change, looked at the 600-mile
Wilkes Basin in East Antarctica, which, if it melted, has enough ice to
raise sea levels by 10 to 13 feet*. Researchers found that the region was
vulnerable to melting because it’s held in place by a small “ice plug”
that may melt over the next few centuries, meaning East Antarctica could
“become a large contributor to future sea-level rise on timescales
beyond a century,” according to the article.
“East Antarctica’s Wilkes Basin is like a bottle on a slant. Once
uncorked, it empties out,” Matthias Mengel, lead author of the study, said in a statement.
That uncorking, however, is a relatively distant threat. The
researchers conducted simulations under scenarios with waters that were 1
to 2.5°C warmer than what they are today, and the study’s authors said there was still time to limit warming enough to keep the plug in place. However, the planet is on track to hit 2°C
if major steps to curb climate change aren’t taken, and already much of
the globe’s warming has been absorbed by the oceans. And although the
East Antarctic threat is distant, it’s still a major finding — the study
is the first to look at the Wilkes Basin to determine how the East
Antarctic region might contribute to sea level rise.
“This is unstoppable when the plug is removed,” study co-author Anders Levermann told National Geographic. “The speed [of removal] we don’t know, but it’s definitely a threshold.”
If all of Antarctica were ever to melt, it could raise sea levels by about 188 feet. A 2012 study found that Antarctica’s ice loss had gone up by 50 percent over the past decade, and this year, a study found
a massive Antarctic glacier has entered an irreversible melt, which
could lead to a rise in sea levels of 1 centimeter. That glacier “has
started a phase of self-sustained retreat and will irreversibly continue
its decline,” one of the study’s authors said earlier this year.
Another study from this year found that the shrinking of Antarctic
glaciers can be “highly dependent” on climate variability.
“These new results show that how much melt the Antarctic ice sheet
experiences can be highly dependent on climatic conditions occurring
elsewhere on the planet,” study co-author Eric Steig said.
As for the Arctic, the National Snow and Ice Data Center in Boulder, Colorado announced in March that the region experienced the fifth-lowest winter sea ice cover extent since 1978.